Early 20th century: Rise of the Dreadnoughts
As the 20th century dawned, vessels that would look familiar to our modern eyes as battleships began to be built: steel hulled, with cannons firing explosive shells arranged along the centerline of the main deck. In 1906 however, every one of these early battleships was rendered obsolete when the British Navy launched HMS Dreadnought. At 20,000 tons, with oil-powered turbines for speed and an array of 39 big guns she single handedly changed the balance of power in naval warfare. Battleships of the day were instantly designated “pre-Dreadnought” and “Dreadnought” as every navy in the world consigned their old-guard battleships to defensive actions and began to design ships capable of combating this radically new British design.
In the Russo-Japanese War, these new design philosophies were put to the test on the open sea and it was shown that the newer naval vessels far surpassed what had come before in speed, armor and firepower as the Japanese navy’s newer vessels soundly defeated the less modern Russian navy, leaving dozens of ships on the ocean floor.
World War I: War of the Dreadnoughts
Despite the tremendous advances in sea power acquired by the German and British navies in the build-up to the First World War, their navies were largely concerned with bottling one another up. The British thus dedicated the bulk of their dreadnoughts to a commercial and military blockade to hold the German fleet close to shore. Finally, in late May early June of 1916, the German fleet attempted to break the blockade, resulting in the largest naval battle of World War I: the Battle of Jutland. On the 31st of May the battle was engaged and it was enormous, involving over 250 ships. In the end fourteen British and eleven German vessels were sunk, many going down with all hands resulting in a tremendous loss of life. Though both sides claimed victory, the British achieved their objective of bottling up the German fleet and preventing German mercantile shipping, while the Germans failed to achieve their objective of breaking the blockade.
Near the end of WWI it became clear that air power had a critical role to play in naval operations, especially with regards to anti-submarine warfare. The British Royal Navy had begun experiments with converting merchant vessels into seaplane carriers. For these primitive carriers, the use of seaplanes was essential, since craft could take off from, but not land on these early flight decks. Seaplanes would lift off from the carrier, perform their mission, then land in the sea alongside and be lifted back into the carrier by crane. These experiments were promising enough that the first ship built from the ground up as a carrier, HMS Ark Royal was commissioned in 1914, serving in the Eastern Mediterranean throughout the war.
In 1917, as the war was drawing to a close, the first aircraft carrier designed for land-based fighters to take off and land from was commission, the HMS Furious. Carrying 7-10 Camel fighters, she only took part in a single operation during the war but that was a success. Landing on her deck was extremely dangerous and unpredictable, making Furious difficult to use reliably but naval planners clearly saw the potential, indeed even the necessity of using aircraft to supplement naval forces.
Interbellum: Between Wars
In the period between WWI and WWII, research into naval aviation increased tremendously. Some of this focus on aircraft carriers was a recognition of the importance of naval aviation but some was artificial. The Washington Naval conference was a postwar attempt by Britain, the United States, Italy, France and Japan to limit the power of their navies (Germany was not a part of this agreement since the Treaty of Versailles limited the strength of its navy tremendously). It was thought this would reduce tensions between the great powers. This treaty stipulated tonnage limits, weapons limits and, most importantly, forbade the powers to upgrade their ships except at twenty year intervals. Meaning naval power would only be upgraded (in theory) every twenty years and at a one-for-one basis (each new ship required an outmoded vessel to be destroyed). An important consequence of this was an increased emphasis on aircraft carriers by all nations bound by the treaty. Although the ships themselves could not be upgraded, the treaty placed no limitations on upgrading aircraft, allowing carriers to be effectively upgraded by including more modernized planes.
As it turned out however, the treaty did not last long enough to have a major effect (other than encouraging the construction of aircraft carriers). France and Italy withdrew from the treaty in 1930 and when Japan withdrew as well in 1934, Britain and the United States dissolved the treaty as all parties began to upgrade their navies. The build-up for the Second World War had effectively begun.
In this period between wars the navies of all sides built up their forces both in terms of aircraft carriers and in ever-larger dreadnoughts. The British Royal Navy constructed the following carriers between WWI and WWII: HMS Eagle (1920), HMS Hermes (1924), a totally rebuilt HMS Furious (1925), HMS Courageous and HMS Glorious (1928-1930) and finally on the eve of WWII one of the most famous and beloved British ships of all time, HMS Ark Royal (1938).
The United States constructed its first carriers during this period, making remarkable strides in carrier construction. Indeed many of the carriers constructed during this period became famous for their service during WWII when they were forced into the limelight following the destruction of the bulk of the American battleship fleet at Pearl Harbor. It is often (and truly) said that these well-designed carriers saved the United States from a forced armistice with Japan during the early days of the war. The carriers constructed by the U.S. between wars were: USS Langley (1922), USS Lexington and Saratoga (1925), USS Ranger (1934), USS Yorktown, Enterprise and Hornet (1937-1941) and USS Wasp (1940).
Japan also made great strides in carrier construction between WWI and WWII including the following vessels: Hosho (1922), Akagi (1927), Kaga (1928), Ryujo (1933), Soryu, Hiryu and Shokaku (1937). All of these except the experimental Hosho would take part in the Japanese attack on Pearl Harbor.
Due to the restrictions of the Treaty of Versailles and the need to rapidly build up its armed forces across the board in the preparations for WWII, Germany did not start its carrier, the Graf Zeppelin until after the start of WWII and it was never completed.
On the battleship front, once the Washington Treaty was abandoned, naval planners began to build even larger dreadnoughts than before, still believing that the dreadnought was the key to naval supremacy. As part of this effort, the accomplishment of the Japanese Navy in constructing the two largest battleships yet designed, the Yamato and the Musashi was particularly noteworthy.